Door-operated valve-controlled stack damper for fuel-burning furnaces



Nov. 24, 1925. 1.562.905 JLJ. A. MILLER DOOR OPERATED VALVE CONTROLLED STACK DAMPER FOR FUEL BURNING FURNACES Filed Dec. 7. 1922 2 Sheets-Shes; 1

Nov. 24, 1925- J. J. A-. MILLER DOOR OPERATED .VALVE CONTROLLED STACK DAMPER FOR FUEL BURNING FURNACES 2 Sheets-Shet 2 Filed Dec. '7, 1922 Patented Nov. 24, 1925 JOHN J. A. MILLER, or nnnvnn, COLORADO.

DOOR-OPERATED VALVE-CONTROLLED STACK DAMPER FOR FUEL-BURNING FURNACES.

Application filed December 7, 1922. Serial No. 605,468.

To all whom it may concern:

Be it known that I, JOHN J. A. MILLER, a citizen of the United States of America, residing at the city and county of Denver and State of Colorado, have invented a new and useful Door-Operated Valve-Controlled St t: Damper for Fuel-Burning Furnaces, of which the following is a specification.

My invention relates to a new door operating valve controlled smoke stack damper for fuel burning furnaces in which the fuel is fed to the furnace by Stoker's through the furnace doors, and the objects of my invention are:

First, to provide a smoke stack damper operating mechanism by means of which the damper in the smoke stack is opened when the fuel feeding-in door or doors of the furnacc are opened by the stoker and in which the damper is closed in a predetermined period of time when the door or doors of the furnace are closed by the stoker by a variable time oil controlled valve.

Further, to provide a smoke stack damper operating mechanism which is adapted to be actuated by the furnace door when opened, thereby to open the said damper, the said mechanism being released by the furnace door, when the same is closed, to permit the closing of the said damper, an oil controlled piston valve being connected with the said mechanism for closing the damper within any predetermined period after the furnace door is closed, said piston valve being also raised simultaneously with the opening of the said damper.

Further, to provide a smoke stack damper with mechanism adapted to be actuated by the furnace door when opened, thereby to open said damper, and means connected with said mechanism for closing the damper within a predetermined period after the door is closed, said door also being provided with dampers which are also opened automatically when the door is opened, means being provided for automatically closing said door dampers within a predetermined period after the door is closed, to admit a gradually decreasing volume of air to the furnace during a given period, whereby the combustible gases and floating particles of carbon and tar are consumed, said stack damper being closed independently of the door dampers.

These objects are accomplished by the mechanism illustrated in the accompanying drawings, in which- Figure l is a front view of a furnace equipped with the improved damper operating mechanism for the door and stack dampers.

Fig. 2 is a side view of the front portion of the furnace shown in Fig. 1.

Figs. 3, 4 and 5 are side views in different positions of the cam lever which a-ctuates the stack damper operating mechanism, and which is operated by the furnace door when the same is opened.

Fig. 6 is a horizontal sectional view through the front wall plate of the furnace on the line 6-6 of Fig. 1, showing the furnace door opened.

Fig. 7 is a vertical sectional view through the oil controlled gravity valve and its hous ing which is used for closing the stack and door dampers.

Fig. 8 is a top view of Fig. 7, the cover being removed.

Fig. 9 is a front view of the air pie-heater which is secured to the furnace door, and

Fig. 10 is a vertical sectional view through the door dampers and their supporting frame.

The improved stack damper operating mechanism is adapted to be actuated by the furnace door to open said damper when the door is opened but the invention also contemplates the employment of a smoke abat ing mechanism, or oxidator, which acts cooperatively with said stack damper and which is attached to the furnace door, such oxidator devices being shown and described in pending applications which were filed by me on the 9th day of October, 1922, for auton'iatically operating oxidators for attachment to furnace doors for abating smoke, Serial No. 593,475, and for automatically operating shutter opening and closing mechanisn'i for furnace: oxidators, Serial No. 593, L74 and also for automatically con trolled smoke abating oxidators for attachment to furnace doors, filed August 1, 1922, Serial No. 579,050, any one of which may be used in connection with the improved stack damper operating mechanism.

Referring to the accompanying drawings:

The numeral 1 designates the front wall plate of a furnace, 2 the boiler, and 3 the smoke stack which is provided with an ordinary circular damper 4, which is secured upon a rod 5, which extends transversely through the stack and is pivotally mounted in suitable bearings 6, preferably ball bearings, which are secured to the stack as clearly shown in Fig. 1. One end portion of the damper rod 5, extends beyond its bearing and has rigidly mounted thereon, a short lever arm 7, to which the upper end of a connecting rod 8 is pivotally secured, the lower end of which is also pivotally secured to a lever arm 9, rigidly secured upon one end of a short horizontal shaft 10, which is mounted in bearings 11, which are bolted to the front plate 1 of the furnace, the shaft 10 being positioned about on a line with the upper edge of the usual fire door 12 of the furnace and to the right of the hinged edge of the door when the said door opens toward the right. Upon the outer end of the shaft 10 is rigidly secured a tappet 13, which normally lies in a horizontal position and which is adapted to be engaged by the upper edge of the fire door when the said door is opened, whereby the tappet is swung from a horizontal to a vertical position, which movement is transmitted to the connecting rod 8 by which the stack damper is also turned from a horizontal or closed position to a vertical or open position. In order that the tappet may be swung in an arc of a quarter of a circle by the upper edge of the lire door, the door engaging edge of the said tappet, when the tappet is in a horizontal position, inclines at an angle of about thirty degrees to a horizontal line for a portion of its length as shown by let, and then merges into an edge portion parallel with a horizontal line as shown by 15,. and then terminates in a vertical edge portion or heel 16, as clearly shown in Figs. 3, 4 and 5, so that as the up per edge of the outwardly swinging door moves against the said tappet, the tappet is swung upward through an arc of a uarter of a circle, when the door passes unc er the heel 16, and thus holds the tappet in an upright position as long as the door remains wide open, the stack damper being held open during the same period. lVhen the upper edge of the door moves out from under the heel 16, as the door is swung to a closed position, the stack damper gradually closes by an oil controlled gravity valve, which is arranged and constructed as follows:

The valve proper is mounted in a metal housing 17, which is secured to the front wall of the furnace by bolts 18, which pass through apertured ears 1.) on the sides of the housing. The housing comprises an upper rectangular chamber 20, from which depends' an oil holding cylinder 21, which opens into the chamber 20. A hollow piston 22 is mounted in this cylinder, the lower end wall of which is provided with a circular axial hole 23, and its upper end is in the form of four radial arms or spokes 24, to which is integrally connected an axial hub 25, in which is inserted the reduced portion of a piston rod 26, in the form of a rack bar having annular teeth 27, the bar being held in the hub by a pin 28, which passes through the hub and through a groove in the said reduced portion of the rack bar or piston rod as it will hereinafter be termed.

The piston rod has an axial hole 29, extending through the same, the lower portion of which is threaded, and a stem 30 is screwed into this threaded portion of the hole, and extends through the hole 23 in the bottom of the piston. The portion of the stem projecting through the bottom of the piston is reduced in diameter, as shown at 31, to form a shoulder 32 at the junction of the two diameters, and a disk valve 33, having an axial hole, is slipped on the reduced portion 31 and is normallyheld against the shoulder 32 by a spiral coil spring 34, which surrounds the reduced portion of the stem and is held in place by a pin which passes through the reduced portion and engages the lower coil of the spring.

The housing is closed by a cap 36, having a threaded hole 37, in line with the axial hole 29 of the piston rod, which is normally closed by a screw 38. The upper end of the stem 30 is formed with a screw driver slot, and by passing a screw driver down through the hole 37 in the cap and into the hole 29 in the piston rod, the valve stem 30 may be adjusted to vary the distance between the disk valve 83 and the b'ottom end wall of the piston, by which the period required for the piston to make its downward stroke through the oil in the cylinder may be lengthened or shortened to meet requirements, for a reason to be hereinafter set forth, and the spring 34L permits the disk valve to move downward away from the opening 23 under the pressure of the oil when the valve is raised so as to permit free passage of the oil through the piston. A shaft 39 is mounted in the side walls of the chamber 20 and has rigidly mounted thereon a segment gear i-O which meshes with the toothed piston rod 26. The shaft 39 extends beyond the inner side wall -of the housing and a lever arm 41 is rigidly secured upon its end, the free end of said lever arm being pivotally secured to the connecting rod 8. The arm 41 is of the same length as the lever arms 7 and 9 which are connected to the upper and lower ends, respectively, of the connecting rod 8, and therefore, these three lever arms turn in unison, and in arcs of the same radius.

The outer portion of the shaft 89 is supported in a bearing 42, and the portion of the rod 8, midway between the shaft 39 and the upper end of the said rod, has pivotally connected thereto an arm 43, which is connected by a pivot bolt to a bearing a l, the arm 4-3 being similar in all respects to the arms 7, 9 and 4-1. The arm a3 serves to steady the movement of the upper portion of the rod 8.

d hen the rod 8 is lifted by the engagement of the furnace door 12 with the tappet 13, the stack damper a is thereby opened, as previously shown, and simultaneously with the opening of the said damper the shaft 39 is given a quarter rotation by which the segment gear 10 is correspondingly turned, and lifts the piston 22 to the limit of its upward stroke where it remains as long as the door 12 is open to its full extent, but when the door is closed the tappet 13 is thereby released and the piston 22 begins to drop by gravity, the time required for the piston to drop from its highest to its lowestposition being determined by the position of the dish valve 33 with respect to the bottom wall of the piston. The downward movement of the piston causes the gradual clos-i g of the damper 4, and when the damper is fully closed it 'remains closed until the lire door is again opened as will he understood.

The stack damper a is adapted to be operated cooperatively with any one of the improved smoke abating mechanisms pre- 'viously referred to, and in the accompanying drawings l have shown the furnace door 12 equipped with one of these mechanisms, a description of which is as follows: i

The door is provided with a circular opening 45, and upon the outside of the door is bolted a rectangular frame &6, having apertured lugs through which are passed bolts ll, which also pass through the door and through lugs lS on an air heating device or prcheater 48, which is thus secured to the inside of the door. The preheater it illustrated in Figures (3 and 9, comprises a dared band, which at its smaller end is slightly greater in diameter than the opening -l5 in the door. This band is integrally connected by a series of thin radial plates 44), with a central tubular member 50, which somewhat longer than the width of the hand, and the outer edges of the plates 49 are outwardly curved from the edge of the band to the outer end of the tubular memher iii).

lladial plates 51 also extend inwardly f om the hand and alternate with the plates The frame 46 on the outside of the door is of the same diameter as the hole l5 in the door and is provided with a series of overlapping shutters 52 in the form of thin metal horizontal blades having apertured lugs on their opposite ends for the recep tion of pivot pins 5% which pass through the sides of the frame. The central shutter has a lug 53 on one end only, and upon the opposite end of this shutter is riveted the foriied end of a shaft 55, which extends through the adjacent side of the frame L6, and through the sides of a housing 56,which is in all rcspects a counterpart of the housing 17 hereinbefore described, and therefore needs no separate description. The shutters are connected to turn in unison, by a bar 5 which lies between and is pivotally connected to pairs of lugs or ears 5*, which are formed on the lower edges of the shutters,and centrally of their length.

The shaft carries a segment gear, simi .lar to the gear ell), which meshes with a toothed piston rod similar to the rod 26, which carries a valved piston in all respects SlLlliftl' to the piston 22, which works in an oil holding cylinder 21 forming a part of the said housing. The housing 1? and its valve, which operates the stack damper, are sli htly larger than the housing and its valve, but in other respects are identical as above stated.

The shaft passes through the housing 56, and its outer end carries a tappet 57, which, when the door is opened, is adapted to be engaged by radial abutment edge on a circular horizontal plate 59 which is adjustably mounted on the hinge pin 60, of the door 12. The back edge of this plate straight and bears against the front wall of the furnace, as shown in Fig. 6, by which the plate is held against a turning movement on the said hinge pin. As the door is swung open, the tappet 57 first engages the edge of the plate by which it is turned from a vertical to a horizontal position and it then passes under the plate by which it is held in a horizontal position until the door is again closed when the tappet passes out from under the plate, thus permitting the shutters to be gradually closed by the descent of the oil controlled gravity valve in the housing 56.

The bottoms of the cylinders are slightly concaved and are provided with drain holes 61. which are normally closed by screws 62, by removing which, the oil in the cylinders may be drawn off.

In operation the cylinders are filled with suitable oil and the valve in each piston is adjusted to control the flow of oil through the piston so that each piston will descend to the limit of its downward stroke within a given period, the valve of the piston which operates the stack damper, being adjusted to cause its piston to descend more slowly than the piston which controls the 'door shutters 52.

Assuming that the pistons are at the limitof their downward strokes, the shutters 52 will be closed thus preventing air from entering the furnace through the prelicater and the damper will also be closed, thus cutting off the draft through the smoke stack and therefore preventing the escape of heat through the said stack. hen it is necessary to stoke the furnace. the fire door opened and the tanpet 57 strikes the straight edge 58 of the plate 59, and is tilted over from a vertical to a horizontal position, and then passes beneath the plate, this move mentof the tappet giving the shafta quarter rotation by which the shutters 52 are swung wide open and the piston in the cylinder 21 is raised to the limit of its upward stroke. When the door 12 is wide open, as shown in Fig. 6, it engages the tappet 13 and swings the same from a horizontal to a vertical position. and thestack damper t is opened through the mechanism previously described and the piston 22 is raised to the limit of its upward stroke, and the damper l: is held open and the piston 22 is held in a. raised position by the engagement of the heel 16 of thesai'd tappet 13, wit-h the upper edge of the door. The shutters 52 and damper 4 remain open during the coaling operation or as long as the door is open. but when the door is closed the tappet 13 is first released and the damper 4 begins to close, then, the ta-ppet 57 passes from beneath the plate 59 and the shutters 52 begin to close, the time required for the complete closing of the shutters being determined by the adjustment of the disk valve of the piston controlling the said shutters. During the closing of the shutters, air in a gradually decreasing volume is admitted to the furnace through the preheater and is thoroughly mixed with the floating particles of tar and carbon and with the combustible gases, causing practically complete combustion of these particles, and of the gases, and the consequent elimination of smoke.

As the piston 22, governing the closing of the stack damper 4, is arranged to close the same more slowly than the shutters 52 are closed, any unconsume'd floating products and gases will be carried out through the stack with the air which passes through the. preheater. and while the damper is wide enough open to induce suiiicient draftthrough the stack for this purpose. But

when complete combustion of these particles and gases has been accomplished and nothing in the nature of smoke remains, the damper 4t closes, thus preventing the escape of heated air through the stack.

Having described my invention, what I claim as new and desire to secure by Let-- ters Patent, is:

The combination with a furnace having a stack and a fire door, a rod pivotally mounted in the stack having a damper thereon, and a lever arm on one of its ends, a shaft on the furnace having a lever arm on one end and a rod connecting said lever arms; of a tappet on the other end of the shaft having an inclined edge terminating in a heel, said inclined edgeheing adapted to be engaged by the top edge of the door when the door is opened, whereby the shaft is turned and the damper thereby opened, said tappet being turned by the door until its heel rests upon the edge of the door, whereby reverse movement of the mechanism is pre vented while the door is open, and gravity means connected to the rod which connects the levers, whereby the damper is closed in a predetermined period after the door is closed.

In testimony whereof I affix my signature.

JOHN J. A. MILLER. 

